Naphthalocyanine complexes as potential photosensitizers for photodynamic therapy of tumors.

In the present paper information about the synthesis and results on the pharmacokinetic and experimental photodynamic therapy (PDT) of naphthalocyanines are given. The photodynamic activity of differently substituted zinc(II)- and silicon(IV)-naphthalocyanines using liposomes or Cremophor EL as drug-delivery systems is shown on different tumor models. For the evaluation of the phototherapeutic effect different assessment criteria were used, including light and electron microscopy observations. The main conclusions which can be arrived at on the basis of our findings are the following: silicon(IV)-naphthalocyanine seems to be not a very effective tumor sensitizer, especially in the treatment of pigmented melanoma, while zinc(II)-naphthalocyanines appear to be very promising for PDT of tumors. Their selective targeting and slow clearance from tumor tissue, fast clearance from skin and pronounced phototherapeutic effect on different tumor models and especially at melanotic tumors, even after application of low drug doses, make this group of photosensitizers very attractive for successful PDT of cancer. © 1999 Society of Photo-Optical Instrumentation Engineers.